For those that are new to using a microscope to identify fungi I thought I would post this illustration of the value of using the 100x oil objective and a dash of cotton Blue for seeing spore ornamentation.

I was looking at Aspergillus niger (on mouldy bread) and thought I might get away with using my dry 60X objective to look at the spores. It's a Plan APO objective and is very good quality. Here are the results.

Spores under 60X dry objective

I couldn't find a Aspergillus with that size smooth spores so I thought I would have a look with the 100x oil objective.

The same spores under 100X oil objective.

Again with the 100X oil but here there is a slight lensing effect and contrast increase as the spores were trapped in a bubble of air.

Using the 100x objective is also good for seeing the spore wall thickness and faint germ pores.